Seat ejection gun firing pin control device



Feb; 14, 1961 J. MARTlN SEAT EJECTION GUN FIRING PIN CONTROL DEVICE 2 Sheets-Sheet 1 Filed May 31, 1957 2,971,729 SEAT EJECTION GUN FIRING PIN CONTROL DEVICE Filed May 51, 1957 J. MARTIN Feb. 14, 1961 2 Sheets-Sheet 2 SEAT EIECTION GUN' IRING PIN CONTROL DEVICE James Martin, Southlands Manor, Southlands Road, Denham, near Uxbridge, Middlesex, England Filed May 31, 1957, Ser. No. 662,883 Claims priority, application Great Britain June 7, 1956 13 Claims. (Cl. 244-122) This invention relates to seat ejection mechanisms for aircraft.

In my U.S.A. patent specification No. 2,467,763 there is described a seat ejection mechanism for ejecting an airman from an aircraft. This mechanism is operated by gas pressure following the firing of an ejection gun.

Before the airman can be safely ejected it may be necessary to jettison some part of the aircraft such as an impenetrable cockpit canopy or hood. The method of releasing locks and relying on aerodynamic forces to carry away the hood is not always satisfactory and, in some circumstances, manual assistance is also insufiicient.

In the specification of my pending U.S.A. patent application Serial No. 501,685 now Patent No. 2,937,829 is described a gas pressure operated mechanism for jettisoning the hood, and further mechanism whereby, upon the operation of a combined control by the airman, a first gun is operated to jettison the hood and, after a predetermined interval set by a time delay mechanism, to allow the jettisoned hood to fly safely clear of the path of the seat when ejected, the seat ejection gun is fired.

There may be circumstances when it is desired'to jettison the hood in readiness for ejection of the seat, but subsequent seat ejection is then not required.

The present invention relates to such mechanisms having alternative operation providing either for the jettison of the hood followed automatically by the ejection of the seat or jettison of the hood alone.

One object of the present invention is to provide an improved form of time delay and seat ejection gun firing mechanism.

An object of one form of the invention is to provide an interlock device which inhibits operation of the time delay mechanism controlling firing of the seat ejection gun so long as the hood remains in position and which is released upon jettisoning the hood.

An object of another form of the invention is to provide means whereby the hood may be jettisoned preparatory to possible ejection of the seat thereby removing a first restraining means for preventing firing of the seat ejection gun but leaving in position a second restraining means which may subsequently be removed.

According to the present invention, there is provided a.

seat ejection mechanism of the type comprising an ejection gun adapted for launching a seat from an aircraft through an opening normally covered by a jettisonable hood, as shown in U.S.-Patent No. 2,708,083. The timedelayed fixing mechanism for the seat ejection gun has first and second restraining means'independently acting to prevent operation of the firing mechanism, one restraining means being released by jettison of the hood.

In order that the invention may be readily carried into effect, one embodiment will now be particularly described by way of example, with reference to the accompanying drawings, in which:

Figure 1 is an exploded view of a time-delayed firing mechanism and nited States Patent As shown in Fig. 2 of the drawings, a breech structure 1 defining a breech chamber 2 is threaded into the open upper end of an expansion cylinder 3 so as to make a gas tight joint therewith. Openings 4, 5 are formed in one end of the structure 1 and place the cartridge chamber 2 in communication with the interior of cylinder 3. Breech structure 1 is adapted to receive an explosive cartridge 6 with the rim 7 thereof pressed against the rim of the breech opening. A screw threaded breech block assembly 8 is screw threaded in the breech opening 18.

As also shown in Fig. l, the breech block assembly 8 is unitary and includes a tubular housing 9 provided at the ends thereof with a top sleeve 10 and a screw threaded base 11, all fastened together, e.g., by welding. The top sleeve 10 is provided with an inner groove 12 and a substantially circular expansion spring 13 snaps into said groove 12. The top sleeve 10 may be provided with projecting teeth 14 or circulated so that a correspondingly shaped spanner may engage the teeth 14 for the purpose of screwing or unscrewing the firing unit breech block assembly 8 into or from the breech opening 18 in the breech housing. The base 11 is pierced to permit protrusion of the striker 15 of the firing pin 16. The breech block assembly further includes a firing pin carrier 17 of generally cylindrical construction. Thecarrier 17 is provided with an axial counterbored opening 19 from end to end and is described below in greater detail.

The body of the firing pin 16 comprises a part cylin-.

drical portion 20 and portion. A flange 22 is provided at the junction between the cylindrical portion 20 and the depending portion 21. The striker 15 of the firing pin 16 projects from the lower end of the depending portion 21. One of the walls of the depending portion 21 comprises a rack 23 extending part of its length and forming part of the time delay mechanism as described below.

The upper end of the firing pin 16 is longitudinally slotted at 24 to form a forked end having a transverse pivot pin 25 carrying a roller 26. A first retaining member in the form of a wedge shaped sear 27 is inserted with sliding fit through the slot 24 beneath the roller 26 and this roller 26 is held against the sear 27 by a firing pin impelling spring 28 which abuts flange 22 at one end thereof and abuts 17 by bolts, the complete assembly being retained in the top sleeve 10 by the retaining spring 13.

fixed thereon, the pinion 35 being arranged to engage of the firing pin 16. The spur wheel 36 is arranged to mesh with a pinion 37 carried by the secondary shaft 32, the latter shaft also carrying a sour wheel 38. Freely and co-axially mounted on the shaft 31, i.e. so as to be rotatable relative thereto, are a star wheel 3? and an integral pinion 40 which meshes with the spur Wheel 38, and, as shown in Figure 2, an escapement rocker 41 co-operates in the usual manner with the star wheel 39 to form a clock-type escapement. Thus the escapement is connected via the gear train 40, 38, 37, 36, 35 to the rack 23 and acts to retard the movement thereof under the action of spring 28.

When the sear 27 is withdrawn by a pull exerted on a manually operated actuating cable, not shown, which may be connected to a removable face screen as shown in my US. Patent No. 2,708,083 and which cable is connected to the sear 27 by hook 42, the firing pin 16 is impelled by the spring 28, the escapement retarding the motion of the rack'part 23 in known manner. When the rack point 23 runs out of engagement with pinion 35, the firing pin is no longer restricted and is driven downwards by the spring 28 so that the firing pin projects through an aperture 43 in the base 11 to strike the detonator of cartridge 6. J

The delay provided by the time delay firing mechanism until the seat ejection cartridge 6 is fired to eject the seat is calculated to ensure such firing only after the jettisoned hood is clear of the projected trajectory of the ejected seat and its occupant.

Further restraining means for maintaining the time delay mechanism inoperative until safe completion of all previous operations, comprises a displaceable bridge member .7 pivoted on a pin 48 carried between a pair of lugs 49, 50 projecting from the end cap 29. The bridge member 47* includes on at least one of the arms thereof a second retaining member in the form of a cam surface 51 adapted to engage the protruding ends of the pivot pin supporting the roller 26. The slope of the r cam surface 51 is such that the push of the impelling spring 25 upon the firing pin 16 would be normally sufficient to pivot the bridge member 47 upwards out of the path of the pivot pin 25 but for a holding member 52 normally abutting the top of the bridge member 47 i as described below.

When the hood of the aircraft is normally positioned over the cockpit (as shown, for example, in US. Patent No. 2,467,763) a member integral therewith, part of which is shown at 53 occupies the position shown in Fig. 2 relatively to the time-delay and firing mechanism described above. The member 53 carries a depending socket 54 having a threaded inner face 55 to receive a sleeve 56. The sleeve 56 retains the holding member I 52 which is a plunger urged downwards upon the bridge member 47 by a compression spring 57. Thus, the time delay mechanism remains inoperative and firing of the cartridge 6 is prevented even after removal of the sear 27 so long as the hood is normally positioned and holds down the bridge member 47*.

When the hood is jettisoned, the holding 5'2 is removedwith the hood and the firing pin 16 is freed to move downwardly.

Alternatively, after jettisoning of the hood, the firing pin may be retained by the sear 27 until such time as the sear is withdrawn, should it be decided subsequently to eiect the seat. a

When inserted in the slot 24, the sear 27 is positioned by a pin 58 which abuts the firing pin 16 at one side of the slotted portion 24 and may be locked against withdrawal by insertion of a safety pin in a hole 59 provided.

To permit the free'withdrawal of the sear 27 from the slot 2 the pin 48 carries a roller 60 between the lugs 49, 50 upon which the wide end of the sear 27 rests. The hook end of the sear 27'similarly rests on a roller 61 carried on a pin 62 extending between a further pair of lugs 63, 64.

it will be apparent that the invention can be variously modified and changed within the scope of the appended claims.

I claim:

1. in an aircraft having a displaceable exit cover and a seat ejection device including an ejection gun adapted for launching a seat from the aircraft, said gun comprising a structure defining a breech chamber which is adapted to receive anexplosive cartridge therein, firing mechanism for said ejection; guncomprising a housing; a firing pin carried by-said -housing and biased for movement from a locked position towards a released position; a striker-carried bysaid firing pin for detonating, as the said firing piri movesintoits released position under the action of its biasing, an explosive cartridge placed in said breech chamber; a first retaining member simultaneously engaging said firing pin and a first part fixed relatively to said housing to retain said firing pin in its locked position; a displaceable member carried by a second part fixed relatively tosaid housing; a second retaining member carried by said displaceable member so as to be movablewith the latter relatively to said housing and to said firing pin between a restraining position in which said second retaining member engages a part of the said firing pin and a released position in which said second retaining member is disengaged from such part of the firing pin; and holding means coupled to said exit cover and normally engaging said displaceable member so as to hold said displaceable member and its second retaining member in their restraining positions until the said exit cover is displaced, whereupon said holding means is automatically withdrawn, permitting said displaceable member and said second re taining member to move into their released positions, said first and second retaining members being independent of one another and operable in any order. 7

2. A firing mechanism as recited in claim 1, in which the housing contains a time delay mechanism arranged and positioned to retard the movement of the said firing pin into its released position when it has been released by both said retaining members.

3. A firing mechanism as recited in claim 1, in which said displaceable member is pivotally mounted on said part fixed relatively to said housing and in which the said second retaining member comprises a cam surface on said displaceable member.

4. A firing mechanism as recited in claim 3, in which the said holding means comprise a holding member attached to the said cover and normally bearing on the said pivotally mounted displaceable member to hold the latter and said cam surface in their restraining positions until the said cover is displaced.

5. A firing mechanism as recited in claim 4, in which the said holding member comprises a spring biased plunger.

6. A firing mechanism as recited in claim 3, in which the said displaceable member is of inverted U-shape, a side arm thereof being provided with the said cam surface to engage the said part of the firing pin.

7. A firing mechanism as recited in claim 1, in which the said firing pin has a slot therein, and in which said first retaining member comprises a wedge-shaped sear normally positioned in said slot and is adapted to be manually withdrawn therefrom.

8. A firing mechanism as recited in claim 1, in which. the housing contains a time delay mechanism arranged and positioned to retard the movement of the said firing pin into its released position when it has been released by both said retaining members.

9. A firing mechanism as recited in claim 3, in which the said time delay mechanism comprises a toothed rack on the side of said firing pin; a rotatable pinion positioned to mesh with said rack; and an escapement mechanism arranged and positioned to retard the rotation said pinion.

10. A firing mechanism as recited in claim 1, in which the said housing is adapted for bodily insertion into and securement in, and for bodily removal from, the said breech chamber.

11. For an aircraft having a displaceable exit cover and a seat ejection device including an ejection gun adapted for launching a seat from the aircraft, said gun comprising a structure defining a breech chamber which is adapted to receive an explosive cartridge therein, fir ing mechanism for said ejection gun comprising a housing adapted for:bodily insertion into and securernent in, and for removal from, said breech chamber; a firing pin mounted in said housing and biased for movement from a locked position towards a released position; s striker carried by said firing pin for detonating, as the said firing pin moves into its released position under the action of its biasing, an explosive cartridge placed in said breech chamber; a toothed rack on the side of said firing pin; a rotatable pinion positioned in said housing to mesh with said rack; an escapement mechanism arranged and positioned in said housing to retard the rotation of said pinion; a first retaining member comprising a manually releasable wedge-shaped sear normally positioned in a slot in said firing pin and simultaneously engaging said firing pin and a first part fixed relatively to saidhousing to retain said firing pin in its locked position; a displaceable member pivotally mounted on a second part fixed relatively to said housing; a second retaining member comprising a cam-surface carried by said displaceable member so as to be pivotal with the latter between a restraining position in which said second retaining member engages a part of the said firing pin and a released position in which said second retaining member is disengaged from such part of the firing pin; and a holding member attached to said exit cover and comprising a spring-biased plunger normally bearing on said pivotally mounted displaceable member so as to hold the latter and its second retaining member in their restraining positions until the said exit cover is displaced, whereupon the said holding member is automatically withdrawn, permitting said displaceable member and said second retaining member to move into their released positions, said first and second retaining members being independent of one another and operable in any order.

12. In an aircraft having a displaceable exit cover and a seat ejection device including an ejection gun adapted for launching a seat from the aircraft, said gun comprising a structure defining a breech chamber which is adapted to receive an explosive cartridge therein, firing mechanism for said ejection gun comprising a housing adapted for bodily insertion into and securement in, and for bodily removal from, said breech chamber; a firing pin mounted in said housing and biased for movement from a locked position towards a released position; a striker carried by said firing pin for detonating, as the said firing pin moves into its released position under the action of its biasing, an explosive cartridge placed in said breech chamber; a retaining member normally simultaneously engaging said firing pin and a part fixed relatively to said housing to retain said firing pin in its locked position; and a time delay mechanism arranged and positioned within said housing a retard the movement of the said firing pin into its released position when it has been released by said retaining member.

13. A firing mechanism as recited in claim 12, in which the said time delay mechanism comprises a toothed rack on the side of said firing pin; a rotatable pinion positioned in said housing to mesh with said rack; and an escapement mechanism arranged and positioned within said housing to retard the rotation of said pinion.

References Cited in the file of this patent UNITED STATES PATENTS 2,569,638 Martin Oct. 2, 1951 2,708,083 Martin May 10, 1955 2,726,055 Musser Dec. 6, 1955 FOREIGN PATENTS 748,956 Great Britain May 16, 1956 763,581 Great Britain Dec. 12, 1956 

